only 1 drain bolt

i've been changing my oil in my 87 gt ever since i got the car and i have only been draining the oil from one drain bolt because that is all i have ever seen.

i was looking around here yesterday and in the haynes manual and realized there should be 2 oil drain bolts in the oil pan. i jacked up my car last night and looked around and still only saw one.

do i have an aftermarket oil pan or am i just blind? the one i see is on the bottom of the oil pan, towards the back, kind of off centered toward the drivers side. where would the other one be because i looked around everywhere, even the sides and did not see another plug? does anyone have a picture?

thanks